Luke McFarlane

Installing firmata fails using `ruby-2.2.2` due to old version of serialport, so this PR fixes that issue. Test results: ``` # Running: .................. Fabulous run in 0.006417s, 2804.8336 runs/s, 2493.1854...

I unfortunately haven't been able to run tests to see if they still pass. See https://github.com/shokai/arduino_firmata/issues/46 for details.

I have loaded SysexLedBlinkFirmata onto my Arduino and set `ARDUINO` variable on my env correctly. `bundle install` succeeded although I had to bump version of `serialport` (see https://github.com/shokai/arduino_firmata/pull/44). ``` arduino_firmata$...

This fixes issue when using `ruby-2.2.2`.